Flotation process to produce separate aluminum silicates and zircon concentrates from a heavy mineral beach sand concentrate



United States Patent FLOTATION PROCESS TO PRODUCE SEPARATE ALUMlNUM SILICATES AND ZIRCQN CONCEN- TRATES FROM A EEAVY RAL BEACH SAND CONCENTRATE Robert E. Eaarson, La Grange, and Charles W. Jonaitis,

Chicago, BL, assignors to Armour and Company, Chicago, 11]., a corporation of Delaware No Drawing. Filed Dec. 16, 1960, Ser. No. 76,131 6 Claims. (31. 209166) This invention relates to a method for concentrating the aluminum silicates and zircon in sand deposits which are usually known as beach sands. More particularly this invention relates to a method for making a bulk separation of the aluminum silicates and zircon from a nonmagnetic, non-conductive fraction of beach sand concentrate.

Beach sands of the type with which the present invention is concerned may be found along the seashore, but are also found in large inland deposits in Florida and elsewhere. These sand beds or deposits are composed principally :of quartz, While containing a small proportion of valuable minerals, among them being titanium oxide minerals like ilmenite and rutile, as well as other heavy minerals such as kyanite-sillimanite, zircon, staurolite, and dumortierite. Usually the content of quartz in these sands will be at least 90% while the content of the various heavy minerals may vary from a trace to upwards of 4%.

The most valuable product at the present time derived from these beach sands is the titanium oxide minerals. These and other conductive and magnet-responsive heavy minerals are being recovered from beach sand deposits by complicated and expensive procedures. For example, the steps in one of these processes involves passing the beach sands through a series of spiral concentrators to make a rough separation of the titanium oxide and other heavy minerals from the quartz. Following the rougher separation, there are cleaner and recleaner spiral circuits to upgrade the rough concentrate, and a large amount of the middling material is recycled through these circuits to increase recovery. The titanium minerals in the heavy mineral concentrate are then further separated and concentrated by electrostatic and magnetic separators. The electrostatic separation removes the ilmcnite and rutile while induced roll magnets are employed to remove the staurolite and dumortierite.

The resultant nonconductive, non-magnetic reject fractions from this operation contain minerals which are in themselevs valuable. The composition of this beach sand concentrate ore is approximately 40 to 50% aluminum silicates, also referred to as the kyanite-sillimanite fraction, to zircon, and 25 to quartz. It is with these fractions that the present invention is principally concerned.

The problem involved in using such ores to obtain an aluminum silicates and zircon product of high grade in economically feasible recoveries has heretofore received little attention. The industry has always realized that this discarded material contained valuable heavy minerals but no commercially feasible method has up to now been devised to obtain the minerals in the proper grade and recovery. Applicants have solved the problem and have provided through this invention a flotation method which enables the bulk concentration of the valuable aluminum silicate and zircon fractions from the non-magnetic, non-conducting fraction of beach sand concentrates.

It is therefore a general object of this invention to provide a method for concentrating the aluminum silicates and zircon in beach sands, and specifically, to

3,ll7,924 Patented Jan. 14, 1%64 ice provide a flotation method for accomplishing this result from preprocessed beach sand concentrates. More specifically, it is an object of this invention to provide a flotation method by means of which the aluminum silicates and zircon in preprocessed beach sands can be separated from the quartz particles of such sands. It is also an object of this invention to provide means for carrying out a bulk separation of the aluminum silicates and zircon in beach sand from the quartz and then, in turn to provide means for carrying out a bulk separation of the aluminum silicates from the zircon. Further objects and advantages of this invention will appear as the specification proceeds.

-In practicing the present invention, the beach sand fraction from which the titanium oxide minerals have been separated is formed into a flotation feed. The particles of this fraction as received range from -30 to +200 mesh.

Although it is not generally necessary to pretreat the feed, some scrubbing and desliming may be necessary to remove clay minerals and other materials from those ores used in the process that contain them. The feed is conditioned directly with an anionic collector. An auxiliary collector such as crude fuel oil and a frother such as pine oil may be added. The use of either an auxiliary collector, which may also act as a froth modifier, and a frother is optional and may be omitted.

Following conditioning of the feed, the pulp is diluted to form an aqueous slurry containing from 10 to 30% solids. To this slurry of flotation feed is added a fluorine containing acid or a mineral acid such as sulfuric acid, or a combination thereof, and the pH of the aqueous feed is adjusted to a pH below about 6.0 and preferably below about 3.0. Then the quartz is depressed by the acid employed and is passed out in the underflow from the cells. The froth product obtained from the flotation operation is made up mainly of the aluminum silicates and the zircon.

The froth product is then preferably scrubbed with a suitable agent such as sodium hydroxide or potassium hydroxide. Specifically, an aqueous slurry of the froth product is formed and from 1 to 2 pounds per ton of caustic is added per ton of product. This slurry or pulp is mixed until the anionic collector employed in the initial separation operation has been removed from the aluminum silicate and zircon particles. This usually takes from 3 to 5 minutes.

The thus prepared pulp may then be conditioned at an alkaline pH with an amine collector in the presence of a depressant selected from the group consisting of dextrins, gums, and starches. Again employing conventional flotation procedures the zircon concentrate is obtained in the overflow leaving an aluminum silicates concentrate in the tailing.

Various anionic collectors may be employed to float the aluminum silicates and zircon from the quarts particles. However, to obtain an aluminum silicate and zircon concentrate of high grade in economically practical recoveries, it is preferred to use as a collecting agent a compound selected from the group consisting of alpha sulfo fatty acids, the alkali metal salts of such acids, the glyceryl and glycol esters of the acids, sulfonated oils and the alkali metal salts of such oils. Examples of preferred compounds are alpha sulfo stearic acid, alpha sulfo palmitic acid, the sodium or potassium salts of these compounds, the beta-hydroxyethylene ester of alpha sulfo stearic acid, the mono and di ethylene glycol esters of alpha sulfo stearic and palmitic acids, sulfonated glyceride oi s and petroleum oils, and mahogany sulfonates.

To achieve the outstanding results of the present invention it is only necessary to add small quantities of the collecting agent to the ore. Usually from 0.1 to about 4.0 pounds of the agent per ton of ore will be satisfactory, with from 0.2 to 1.0 pounds per ton being preferred.

The fluorine containing acid which is used as a depressant is preferably hydrofluoric acid although other fluorine containing acids can be substituted, as well as mixtures of hydrofluoric acid and other fluorine containing acids.

The pH of the flotation slurry in separating the aluminum silicates and zircon from the quarts should not exceed about pH 6.0. Best results are achieved at a pH below 3.0. Part of the necessary hydrogen ion concentration to achieve the desired pH can be supplied by the fluorine containing acid, but for economic reasons it will usually be preferred to use an additional acid, such as sulfuric or hydrochloric acid to maintain the flotation circuit at an acid pH.

In bringing about the separation of the aluminum silicatcs from the zircon concentrate, any amine collector may be employed. Preferably, however, the amine flotation agent is a primary amine containing a hydrophobic 41 silicates from the zircon is usually carried out at an alka- 0 line pH in the range from 7.0 to 12.0 and preferably in the range from 8.0 to 10.0. Since the present invention does not depend for its success on the choice any specific base material, any suitable base may be employed to provide the desired pH. Examples of such bases are sodium hydroxide, potassium hydroxide, sodium carbonate, and the like.

The depressant employed in effecting a separation of Both monoamines 25 and starches. These agents have the effect of depressing the aluminum silicates permitting the zircon to be ob tained as the froth product.

In practicing this invention it is preferred to employ a frothing agent to float the various concentrates. Examples of suitable froth-ers are pine oil and Dov/froth 250. Similarly, it has been found desirable to use a frothing modifier such as kerosene, fuel oil, diesel oil or other petroleum distillates. Such agents have the effect of suppressing the amount of froth while serving the function of what is believed to be a secondary collector for the aluminum silicates and zircon.

The pulp density in the conditioning and flotation circuits may be varied widely. in the conditioning circuit the solids may be as low as 25%. However, to about 85% solids is preferred and solids is considered an optimum condition. In the flotation circuit the solids may run as high as 40% and as low as 10%. A 25% pulp density, however, is especially eflective for flotation.

The flotation operations themselves may be carried out in the usual type of flotation cells provided with means for supplying air to the lower portion of the cells. When the beach sand concentrate has been treated and conditioned as described and the flotation feed is at the desired pH, the aluminum silicates and zircon can be readily floated away from the quartz. Inother words, the aluminum silicates and the zircon will be recovered in the overflow from the cells, while the quarts will be depressed and will pass out in the underflow from the cells. Similarly, the aluminum silicates and zircon concentrates, employing the material described and conditions specified, may be separated with conventional equipment.

This invention is further described in the following specific examples:

EXAMPLE I Preparation of ore Condition ore at solids for 1 minute with 0.25 lb./ton alphasulfo stearic acid, then for 1 minute with 0.5 lb./ton crude fuel oil.

the aluminum silicates from the zircon may, as indicated, 353? machine i g i g be selected from the group consisting of dextrins, gums 4O flfifjjjjj:

REAGENTS AND CONDITIONS Pcr- Alpha- Crude Point 01' Addition Time Float cent pH Sulfo Fuel HF NaOH Dextrin Armac Pine 00nd (Min) Solids sgeaizlic Oil (48%) 164 T Oil 1st Rougher Scrub 1st Rougher for 5 minutes at 20% solids with 1st Zircon Concentrate 2nd Zircon Concentrate ees (O OiDrk *I-Initial, FFinal.

REMARKS-Alpha sulfo stearic acid used as a 10% solution in Wit-T81, crude fuel oil used is No. 6 grade Bunker 0 fuel oil-Dextrin 1G4 obtained from Corn Products1 and 2 Zircon concentrates combined for ana1ys1sArruac T is an acetate salt of a .tullow amine.

IWETALLURGICAL RESULTS Weight Weight Percent Percent Percent Product Grams Percent Heavy Grade 2 Recovery 9 Minerals 1 Quartz Com 34.1 10.4 Zircon Cone 114 22. 9 99. 25 87.7 76.1 Aluminum Silicates Gone 214 43. 0 99. 68 86. 7 85. 8

1 Percent Heavy Minerals attained by heavy media separation. 2 Grade and Recovery obtained by petrograpliic analysis.

EXAMPLE H Preparation of ore Condition ore at 85% solids for 1 minute with 0.50 1b./ton alphasulfo lauric acid, then for 1 minute with 0.5 lb./ ton crude fuel oil.

Flotation machine Fagergren.

Distilled. 5 Temperature 25 C.

REAGENTS AND CONDITIONS Time Float Percent Alpha-Sulfa Crude HF Dextrin Duo- Pine Point of Addition Cond. (Min) Solids pH LauricAcicl (48%) H2804 NaOH 164 macC O11 1st Rougher {"2 Scrub 1st Rougher for 5 minutes at 20% solids with 2.0 lb/ton NaOH, deslime and wash.

9. 5 I O. 08 1st Zircon Concentrate 2% 9 F 2. 0 0. l 0.17 2nd Zircon Concentrate-.. l u 0.04 0 2 "63 1 REMARKS.A1pha-su1f0laulic acid used as a 10% solution in water. Crude fuel oil used is No. 6 Bunker C fuel oil. Dextrin 11th olptained from Corn Products 1st and 2nd Zircon Concentrate combined for analysis. Duomac C 1s a diacetate salt of a coco iamme.

METALLURGICAL RESULTS Weight, Weight, Percent Percent Percent Product Grams Percent Heavy Grade Recovery Minerals Quartz Gone 149 30.1 3.52 Zircon Conc 186 37.5 96. 76 62. 9 91.1 Aluminum silicates Conc 161 32.4 99.64 94. 7 69. 0

EXAMPLE III Preparation of ore Condition ore at 85% solids for 1 minute with 0.25 1b./ton monoethylene glycol ester of alpha sulfo stearic acid, then for 1 minute with 0.5 lb./ton crude fuel oil.

Flotation machine Fagergren. Water Distilled. Temperature 25 C.

REAGENTS AND CONDITIONS Monoethylene glycol Crude Point of Addition Time Float Percent ester of Fuel HF NaOH Dextrin Armac Pine Cond (M' Solids pH Alphasullo Oil (48%) 164 T Oil Stearic a 2. 1st Rougher 2% 0 1 96 Scrub 1st Rougher for 5 minutes at 20% solids with 2.0 lb./Ton NaOH, deslime and wash twice 7. 1st Zircon Concentrate 1A 2% Q 2. 0 0.2 0.17 2nd Zircon Concentrate y 1 trace 0 2 0 17 REMARKs.Monoethy1ene glycol ester of alpha-sullo stcarie acid used as a 10% solution in water. Crude fuel oil used is No. 6 grade Bunker C fuel oil. 1st and 2nd Zircon concentrates combined for analysis. Armac T is an acetate salt of a tallow amine.

METALLURGICAL RESULTS Weight, Weight, Percent Percent Percent Product Grams Percent Heavy Grade Recovery Minerals Quart Cone 161 32. 3 8.10 Zircon Cone 174 34. 9 97. 73 58.1 83.2 Aluminum Silicates Conc 164 32. 8 99. 53 87. 9 64.1

7 EXAMPLE IV Preparation of ore Condition ore at 85% solids for 2 minutes with 0.25 lb./ton disodium alpha sulfo stearate. then for 1 minute with 0.5 lb./ton crude from the aluminum silicates 'm a second aqueous medium containing an amine collector and a depressant selected from the group consisting of dextrins, gums and starches, said second aqueous medium having been adjusted to a fu l on pH of from 7.0 to 12.0 for said separation. gig 51011 machine %ag ergr n. 2. The process as claimed in claim 1 wherein the Temperature 1C anionic collector is alpha sulfo stearic acid.

REAGENTS AND O ONDITIONS Time Float Percent Di-Na Crude HF Starch Armac Fine Point of Addition Cond (Min) Solids pH Alpha-Sulio Fuel (43%) NaOH 3366 '1 Oil Stearate Oil 85 un 0.25 0.5 Rough 2.19 :1 };f

Scrub 1st Rougher for 5 minutes at solids with 2.0 lbJton NaOH, deslime and wash r-, 9.5 I 0.08 1st Concentrateu M 2% 0 1; 2.0 o 2 0.17 4 2nd ZlICOIl Concentrate 1 fig F O 2 017 REnARKs.Di-sodium alpha sulio stearate was prepared in situ by conditioning the ore first with alpha-sulto stearic acid and than treating the ore with a stoichiornetric amount of sodium hydroxide to neutralize the acid. Crude fuel oil used is No. 6 grade Bunker C fuel oil. Starch 3366 is a corn starch obtained from 0 cm Products, 1st and 2nd Zircon concentrates combined for analysis. Armac T is an acetate salt of a tallow amine.

METALLURGICAL RESULTS Weight, Weight, Percent Percent Percent Product Grams Percent Heavy Grade Recovery Minerals Quartz 0 one 174 34. 8 16. 27 Zircon C one 168 33. 5 98. 8O 66. 0 91. 2 Aluminum Silicates Cone 158 31. 7 99. 24 94. 3 65.0

Remarks The ore used in the tests conducted was the resultant nonconductor, non-magnetic product from electrostatic separation and separation over induced roll magnets. The electrostatic separation removed the ilrnenite and rutile while the induced roll magnets removed the staurolite and dumortierite leaving an aluminum silicateszircon-quartz fraction. This had an approximate composition of 45% aluminum silicates, 25% zircon and quartz. Compositions on this and on subsequent products obtained by flotation were determined by a petrographic analysis. Heavy mineral analysis was determined by a heavy media separation.

The analyses indicate an upgrading of minerals in both the aluminum silicates concentrate and the zircon concentrate. Percent heavy minerals essentially is the total heavy mineral grade in each product obtained, with the remainder consisting of quartz. Percent grade indicates the grade of the mineral being concentrated, taking into account both the quartz and other heavy minerals as contaminants. Percent recovery represents that portion of the total mineral appearing in the particular product that is considered to be the concentrate.

We claim:

1. A process for the concentration of quartz, aluminum silicate and zircon from a non-conductive non-magnetic fraction of beach sand concentrate, comprising floating the aluminum silicates and zircon away from the quartz particles in a first aqueous medium containing a fluorinecontaining acid and an anionic collector selected from the group consisting of alpha sulfo fatty acids, the alkali metal salts of such acids, the glyceryl and glycol esters of the acids, sulfonated oils and the alkali metal salts of such oils, said first aqueous medium having been adjusted to a pH not exceeding 6.0 for said flotation step, removing the aluminum silicates and zircon in the overfiow, chemically treating the aluminum silicates and zircon to remove the collector, and separating the zircon 3. The process, as claimed in claim 1 wherein the anionic collector is alpha sulfo palmitic acid.

4. The process, as claimed in claim 1 wherein the anionic collector is monoethylene glycol ester of alpha sulfo stearic acid.

5. The process, as claimed in claim 1 wherein the anionic collector is the monoethylene glycol ester of alpha sulfo palmitic acid.

6. A process for the concentration of quartz, the kyanite-sillimanite and the zircon from a non-conductive, non-magnetic fraction of beach sand concentrate, comprising floating the kyanite-sillimanite and zircon away from the quartz particles in a first aqueous medium containing hydrofluoric acid and alpha sulfo stearic acid, said first aqueous medium having been adjusted to a pH not exceeding 6.0 for said flotation step, removing the kyanitesillimanite and zircon in the overflow and separating the zircon from the kyanite-siilimanite in a second aqueous medium containing an amine collector and a depressant selected from the group consisting of dextrins, gums and starches, said second aqueous medium having been adjusted to a pH of from 7.0 to 12.0 for said separation.

References Cited in the file of this patent UNITED STATES PATENTS 2,082,383 Corbett June 1, 1937 2,185,541 Calm Jan. 2, 1940 2,205,503 Trotter June 25, 1940 2,305,502 Tartaron Dec. 15, 1942 2,341,046 Kirby Feb. 9, 1944 2,414,815 Kennedy et al. Jan. 28, 1947 2,459,219 Duke Jan. 18, 1949 2,460,968 Bert Feb. 8, 1949 2,792,940 Baarson May 21, 1957 2,970,688 Uhland Feb. 7, 1961 3,008,655 Adams et al Nov. 14, 1961 FOREIGN PATENTS 479,072 Canada Dec. 4, 1951 

1. A PROCESS FOR THE CONCENTRATION OF QUARTZ, ALUMINUM SILICATE AND ZIRCON FROM A NON-CONDUCTIVE NON-MAGNETIC FRACTION OF BEACH SAND CONCENTRATE, COMPRISING FLOATING THE ALUMINUM SILICATES AND ZIRCON AWAY FROM THE QUARTZ PARTICLES IN A FIRST AQUEOUS MEDIUM CONTAINING A FLUORINECONTAINING ACID AND AN ANIONIC COLLECTOR SELECTED FROM THE GROUP CONSISTING OF ALPHA SUFFO FATTY ACIDS, THE ALKALI METAL SALTS OF SUCH ACIDS, THE GLYCERYL AND GLYCOL ESTERS OF THE ACIDS, SULFONATED OILS AND THE ALKALI METAL SALTS OF SUCH OILS, SAID FIRST AQUEOUS MEDIUM HAVING BEEN ADJUSTED TO A PH NOT EXCEEDING 6.0 FOR SAID FLOTATION STEP, REMOVING THE ALUMINUM SILICATES AND ZIRCON IN THE OVERFLOW, CHEMICALLY TREATING THE ALUMINUM SILICATES AND ZIRCON TO REMOVE THE COLLECTOR, AND SEPARATING THE ZIRCON FROM THE ALUMINUM SILICATES IN A SECOND AQEUOUS MEDIUM CONTAINING AN AMINE COLLECTOR AND A DEPRESSANT SELECTED FROM THE GROUP CONSISTING OF DEXTRINS, GUMS AND STARCHES, SAID SECOND AQUEOUS MEDIUM HAVING BEEN ADJUSTED TO A PH OF FROM 7.0 TO 12.0 FOR SAID SEPARATION. 